Giving a single dose of nevirapine and a week’s worth of AZT treatment after birth significantly reduces the risk of HIV infection for a child whose mother is not treated during pregnancy or labour when compared with nevirapine alone, according to findings from the NVAZ trial published this week in The Lancet.
The NVAZ trial was carried out in Malawi, and recruited 1119 babies whose mothers did not receive any HIV treatment during pregnancy or labour, either because they had presented late or because they had not taken the nevirapine prescribed for prevention of mother to child transmission.
Infants were eligible if their mothers consented to rapid HIV testing after delivery; 12,355 women were invited to join the study, of whom 5393 tested HIV-negative, 3933 refused an HIV test or did not want to join the study and 1910 infants had problems which precluded participation in a clinical study at that point (preterm babies were excluded from the study).
1119 infants were randomised to either one dose of nevirapine (2mg/kg weight) or to one dose of nevirapine (2mg/kg) plus one week of treatment with zidovudine (AZT) twice daily (4mg/kg). The infants’ HIV status was tested six to eight weeks after birth, and if the child tested positive by viral load test, a sample of blood taken after birth was also subjected to viral load testing to determine whether infection had occurred before or after birth.
One hundred and six infants were subsequently found to have been infected before birth, and were excluded from the analysis, and 135 babies were lost to follow up or had died by weeks 6-8. Of the remaining 865, 12.1% of the nevirapine only group and 7.7% of the AZT plus nevirapine group had been infected with HIV, indicating a protective efficacy of 36%. Efficacy was lower in babies of women with viral load above 100,000 copies/ml.
The researchers say that because a placebo group could not be included for ethical reasons, the study probably underestimates the true benefit of AZT and nevirapine together. Previous mother to child transmission rates of around 28% have been observed in Malawi.
Adverse events did not differ between the two treatment groups (5.6% in the nevirapine group, 7.8% in the nevirapine/AZT group), no deaths were directly attributable to adverse events and no cases of Stevens-Johnson syndrome, hepatotoxicity or serious anaemia were reported.
The authors conclude that trials are needed which extend the duration of the regimen in order to study its impact on breastfeeding, but that the studied regimen could be implemented now for all women who arrive late in the delivery room, who accept an HIV test and who test positive for HIV antibodies after delivery.
Further information on this website
Mother to child transmission - short treatment courses -summary of key research
HIV & AIDS Treatment in Practice # 11 - Preventing mother to child transmission of HIV
Reference
Taha TE et al. Short postexposure prophylaxis in newborn babies to reduce mother-to-child transmission of HIV-1: NVAZ randomised clinical trial. The Lancet 362: 1171-77, 2003.